Thermal fluctuations and bending rigidity of bilayer membranes

Abstract

We present a new scheme to estimate the elastic properties of biological membranes in computer simulations. The method analyzes the thermal fluctuations in terms of a coupled undulatory mode, which disentangle the mixing of the mesoscopic undulations and the high-q protrusions. This approach makes possible the accurate estimation of the bending modulus both for membranes under stress and in tensionless conditions; it also extends the applicability of the fluctuation analysis to the small membrane areas normally used in atomistic simulations. Also we clarify the difference between the surface tension imposed in simulations through a pressure coupling barostat, and the surface tension that can be extracted from the analysis of the low wave vector dependence of the coupled undulatory fluctuation spectrum. The physical analysis of the peristaltic mode is also refined, by separating the bulk and protrusions contributions. We illustrate the procedure by analyzing 1-palmitoyl-2-oleoylsn-glycero-3-phosphocholine and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine bilayers. The bending moduli obtained from our analysis, shows good agreement with available experiments. © 2013 AIP Publishing LLC. [http://dx

Nanoparticle–membrane interactions

“…For example, for a cell membrane tension in the order of 0.05 mNÁm ¡1 and bending modulus values of 15 k B T, the length scale is approximately 50 nm [48]. Simulation [59] and experiment [60] suggest a bending modulus of k » 23 k B T (»10 ¡19 J at 300 K for DPPC gives »60 nm. In what follows, we assume k ¼ 23 k B T (unless otherwise stated) for the calculation of adhesion energy from the critical radius determined experimentally.…”

Quantum effects in graphene monolayers: Path-integral simulations

“…[14][15][16] It has been traditionally considered mainly in the context of biological membranes and soft condensed matter. The great complexity of these systems has hindered a microscopic approach based on realistic descriptions of the interatomic interactions.…”

A computer simulation approach to quantify the true area and true area compressibility modulus of biological membranes

“…14 The mean area of the undulatory surface area A U = ⟨A U ⟩ is often used to represent the fluctuating bilayer membrane. 12,13 Following the capillary wave theory, [26][27][28] …”

“…In our previous work, 14 we employed a Berendsen semiisotropic barostat to simulate bilayers at different surface tensions. This barostat does not produce the correct statistical ensemble and therefore it is not possible to compute the area compressibility modulus from a fluctuation analysis of the membrane area.…”

“…This approach is based on our recent analysis of the spectrum of elastic deformations in a bilayer membrane. 14 …”